1. Field of the Invention
The present invention relates to transmission testing devices and, particularly, to a universal device for manually controlling the operation of solenoids within computer shifted transmissions.
2. General Background
Automatic transmissions in recent vehicles are electronically controlled. Electronic sensors monitor engine conditions and determine the proper transmission gear. The system transmits an electronic signal through a wiring harness to the electronic control module (ECM) of the transmission. The signal activates one of several solenoids to cause the transmission to change to the determined gear. The signal for each specific gear is normally related to a combination of grounded and ungrounded wires in the wiring harness. Since there are many automobile manufacturers, not every transmission responds alike to the same set of signals. As a result, there are transmission test devices for each type of transmission. This leads to the need for mechanics that work on different types of vehicles to have a number of expensive test devices. Transmission related testing devices that the inventor is aware of include the following.
U.S. Pat. Nos. 3,273,384 and No. 3,302,107 are directed to hydraulics and individual component applications and testing and are not related to the electronic transmission controls of today's vehicles.
U.S. Pat. No. 3,482,441 is directed to an accurate and precise method of measuring the quality and time length of a transmission shift. It only measures shifting and does not control it.
U.S. Pat. No. 4,809,541 is directed to testing speed control (cruise control) systems and not automatic transmissions.
U.S. Pat. No. 4,998,437 is directed to limited disassembly of a transmission hydraulic system to hydraulically operate a unit and does not deal with the electrical shifting controls of a transmission.
U.S. Pat. No. 5,060,177 is directed to testing only a specific CHRYSLER.TM. transmission by simulating shifting conditions just as the onboard computer might do and is very complex in operation.
U.K. Patent Application GB 2 019 585A is directed to reading and checking electrical circuits within the transmissions of commercial applications and not to passenger automobiles.
The known test devices do not address the need for a universal test device capable of testing the transmissions of different manufacturers.